Flexible intra-vascular aneurysm treatment stent

ABSTRACT

An intra-vascular aneurysm-treatment stent and a method for lowering pressure within an aneurysm bubble in a blood vessel. A stent coil is insertable into a blood vessel, the coil made of a material sufficiently flexible to move around curves, loops, and corners in the blood vessel. The stent coil is positioned in the blood vessel with selected stent coil portions proximate an opening into either a saccular aneurysm or a fusiform aneurysm. Blood in the lumen of the blood vessel flows past the leading edges and both over the outer surfaces, and under the inner surfaces. A portion of the blood inside the aneurysm becomes entrained with the blood flowing over the outer surfaces. At the trailing edges, the converging blood flows create eddies.

The present application is a continuation of U.S. application Ser. No.15/156,653, filed May 17, 2016; which is a divisional of U.S.application Ser. No. 13/839,775, filed Mar. 15, 2013 (now U.S. Pat. No.9,339,400); which claims the benefit of Provisional Application No.61/764,920, filed Feb. 14, 2013; all the contents of which areincorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to flexible intra-vascular stents and toflow diverters and modifiers, and more particularly to flexible wireintra-vascular stents for treatment of aneurysms in the carotid andvertebral arteries and branch blood vessels extending from the carotidand vertebral arteries into the brain.

BACKGROUND OF THE INVENTION

An aneurysm is a circumscribed dilation of a blood vessel, or cardiacchamber, in direct communication with its respective lumen, usuallyresulting from an acquired or congenital weakness of the wall of theblood vessel, or chamber. An aneurysm occurs when a part of the artery,other blood vessel, or cardiac chamber, swells, either due to damage tothe wall or a weakness in the wall. As blood pressure builds up witheach heartbeat, the wall balloons out at its weakest point, forming ananeurysm bubble. The bubble tends to fill with blood, as blood flowingthrough the lumen is partly diverted through the opening into theaneurysm. As the aneurysm grows, in addition to causing pain and othercomplications, a risk of rupture of the bubble increases. Rupture of ananeurysm in a carotid or vertebral artery in the neck, or in a branchblood vessel extending from the carotid or vertebral artery into thebrain can cause a hemorrhage or stroke, which can be at best severelydebilitating, and at worst deadly. For perspective, aneurysmalsubarachnoid hemorrhage (SAH) occurs about 30,000 times annually in theUnited States. Of these, between ⅓ and ½ of those so afflicted will notsurvive the trip to the hospital.

FIGS. 1 and 2 depict various configurations of aneurysms. In eachdrawing, a generally tubular blood vessel 10 comprises an innerperipheral wall 12, and an outer peripheral wall 14. The innerperipheral wall 12 defines a lumen 16 through which blood 17 flows. Aweak point in the wall 12 has an opening, called a neck, 18. A portionof the blood flow 17 is diverted from the lumen 16 through the neck 18to form and maintain a saccular aneurysm 20. A saccular aneurysm 20 isshown in FIG. 1. FIG. 2 shows a fusiform aneurysm 20′. If the arterialwall weakness is focal, i.e., it does not extend all the way around theartery, the aneurysm is most likely to be saccular. If the weakness iscircumferential, it will more likely be fusiform. In the saccularaneurysm 20, its communication with the lumen 16 is though the aneurysmneck 18. The fusiform aneurysm 20′ by definition does not have a neck.

FIGS. 3A-3B depict a conventional attempt to treat aneurysms. FIG. 3Adepicts a wire stent 30, installed in a blood vessel 10 with a fusiformaneurysm bubble 20′. Referring to FIG. 3B, a raised strut portion 32 ofthe wire stent 30 depicted in FIG. 3A is provided against the bloodvessel inner peripheral wall 12 immediately upstream of the aneurysmneck 18. It is intended that an increase in velocity of the blood flow17 over the raised strut portion 32 will create a pressure drop (dP) ata trailing edge thereof to cause blood 17 in the saccular aneurysmbubble 20 to flow back into the lumen 16 of the blood vessel 10.

FIG. 4 explains why this conventional attempt to treat aneurysms issometimes ineffective, even harmful. At the trailing edge of the raisedstrut portion 32, as in the case of a trailing edge of an airplane, theflow of fluid (in this case blood 17) flows across the apex of the wingand down past the trailing edge. The configuration and positioning ofthe strut 32 in FIG. 3B, however, rather than creating a pressure drop(dP), drawing blood 17 out of the saccular aneurysm 20 and into thelumen 16, instead directs more blood flow 17 at the trailing edge intothe saccular aneurysm 20, thereby achieving an effect opposite of thatwhich was intended. In fact, it can have the effect of directinghigh-velocity blood to strike the inflow zone of the aneurysm, afragile, delicate part.

SUMMARY OF THE INVENTION

In accordance with the invention, a flexible intra-vascular catheter fortreating an aneurysm includes an expanding coil insertable into a bloodvessel, including a curving blood vessel, with coil portions positionedproximate an opening in the blood vessel wall into an aneurysm bubble,the coil portions are configured to receive blood flow in the bloodvessel on their upstream side/leading edge and re-direct the blood flowback toward a central lumen of the blood vessel, thereby creating aneddy effect proximate the downstream side/trailing edge of therespective coil portions, creating a pressure drop (dP) which drawsblood in the aneurysm bubble back into the lumen of the blood vessel,and collapsing the bubble, or at least substantially decreasing pressurein it.

In one embodiment, the coil portions have an arcuate upper surfaceproximate the inner blood vessel wall and facing the opening into theaneurysm bubble, and generally flat inner surfaces facing the lumen ofthe blood vessel. Blood flow on the upstream side/leading edge of eachcoil portion travels over and across the arcuate outer surface and isdirected back down toward the lumen of the blood vessel. Proximate theopening into the aneurysm bubble, on the downstream side/trailing edgeof each coil portion, this downward flow converges with the flow alongthe flat inner surfaces, creating an eddy, with a corresponding pressuredrop (dP). The dP draws blood out of the aneurysm bubble and back intothe lumen of the blood vessel, thereby collapsing the bubble, ordecreasing pressure in it.

In another embodiment, the coil portions have convex outer surfacesproximate the inner wall of the blood vessel and facing the opening intothe aneurysm bubble, and concave inner surfaces facing the lumen of theblood vessel. Blood flow from upstream flows over and across each convexouter surface, and also flows into each successive concave inner surfaceat its respective upstream/leading edge portion, and out of the concaveinner face at its respective trailing edge, being redirected back towardthe lumen of the blood vessel. The converging blood flows at eachrespective downstream/trailing edge portion, create an eddy at eachdownstream/trailing edge portion. Once again, each eddy creates acorresponding pressure drop dP. This dP draws blood out of the aneurysmbubble and toward the lumen of the blood vessel, thereby collapsing thebubble, or decreasing pressure in it.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate preferred embodiments of theinvention and together with the description, serve to explain theprinciples of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of a blood vessel, with a saccular aneurysmlocated on one outer surface of the blood vessel;

FIG. 2 is a side view of a blood vessel with a fusiform aneurysm,defined by a circumferential dilatation of the artery;

FIG. 3A is a perspective view of a coil stent in a blood vessel, used ina conventional attempt to treat a fusiform aneurysm;

FIG. 3B depicts a conventional attempt to treat an aneurism, using thecoil stent of FIG. 3A;

FIG. 4 is a side schematic view depicting the operation of theconventional attempt to treat aneurysms depicted in FIG. 3B, anddemonstrating why the conventional attempt is sometimes ineffective;

FIG. 5 is a side view of a flexible intra-vascular stent, in accordancewith the invention, positioned in a blood vessel proximate an aneurysm;

FIG. 6A is a side cross-sectional view of a first embodiment of theflexible intra-vascular stent of FIG. 5, positioned in a blood vesselproximate an aneurysm;

FIG. 6B is a side cross-sectional view of one coil portion of the firstembodiment of the flexible intra-vascular stent of FIG. 6A;

FIG. 6C is an cross-sectional end view of the flexible intra-vascularstent of FIG. 6A, positioned in a blood vessel proximate an aneurysm;

FIG. 7A is a side view of a second embodiment of the flexible intra-vascular stent of FIG. 5, positioned in a blood vessel proximate ananeurysm;

FIG. 7B is a cross-sectional end view of one coil portion of the secondembodiment of the flexible intra-vascular stent of FIG. 7A;

FIG. 7C is an cross-sectional end view of the flexible intra-vascularstent of FIG. 7A, positioned in a blood vessel proximate an aneurysm;

FIG. 8A is a side view of a blood vessel with a loop defined therein, ananeurysm positioned on a wall of the loop, and the flexibleintra-vascular stent of FIG. 5 positioned in the loop proximate theaneurysm;

FIG. 8B is a side view of a curved blood vessel, with an aneurysmpositioned on a wall of the curve, and the flexible intra-vascular stentof FIG. 5 positioned in the curve proximate the aneurysm.

DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the present preferredembodiments of the invention, examples of which are illustrated in theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

As broadly embodied herein, referring to FIGS. 5-8B, a flexible coilintra-vascular stent 40/60 in accordance with the invention comprises aself-expanding or balloon-expanded generally tubular stent, flexible forgoing around curves, loops, and corners in blood vessels, particularlycarotid or vertebral arteries in the neck, and branch blood vesselsleading off the carotid arteries into the brain. It is preferred thatthe stent 40/60 be made of flexible wire, which in a preferredembodiment is formed of a memory metal such as Nitinol. In anotherpreferred embodiment the stent 40/60 is formed of a non-memory metal,e.g., stainless steel.

Preferred configurations and operation of the flexible intra-vascularwire stent 40/60 in accordance with the invention is explained withrespect to FIGS. 6A-7C.

As broadly embodied in FIG. 6A, a first embodiment of a flexibleintra-vascular wire coil stent 40 is positioned in a generally tubularblood vessel 10, the blood vessel 10 including a peripheral inner wall12, a peripheral outer wall 14, a central lumen 16, and an aneurysm neck18 in the wall 12, allowing blood 17 to flow from the lumen 16 into ananeurysm bubble 20.

Flexible intra-vascular wire coil stent 40 includes a plurality ofsequential coil portions 42, depicted in cross-section in FIGS. 6A and6B. As depicted in FIGS. 6A and 6B, each coil portion 42 includes anupstream leading edge 44, an outer surface 46, a downstream trailingedge 48, and an inner surface 50. Each outer surface 46 defines an arcbetween the leading edge 44 and the trailing edge 48, whereas the innersurface 50 is substantially flat. Moreover, whereas several of the outersurfaces 46 face the inner wall 12 of the blood vessel 10, and the innersurfaces 50 all face the lumen 16 of the blood vessel 12, selected coilportions 42′ have outer portions 46′ facing the neck 18 into theaneurysm 20.

In operation, blood flow 17 in the lumen 16 will flow past the generallyflat inner surfaces 50, with some blood flow 17 being diverted by theleading edges 44′ of the selected coil portions 42′ facing the neck 18,across the outer surfaces 46′, past the trailing edges 48′ and backtowards the lumen 16. Comparing FIG. 6A to FIG. 4, it can be seen thatrather than directing blood flow into the aneurysm 20, as was the casewith the conventional art, selected coil portions 42′ direct blood flowaway from the aneurysm 20 and toward the lumen 16. Some of the blood 17in the aneurysm 20 will become entrained in the blood flow 17 over theouter surfaces 46′ and be directed back into the lumen 16. Moresignificantly, the converging blood flow paths 17 at the trailing edges48′ of the selected coil portions 42′ create eddies 52 proximate thetrailing edges 48′ of the selected coil portions 42′. Each eddy 52results in a pressure drop dP between pressure at the respective outersurface 46′ and the respective trailing edge 48′. The dP generated atthe respective trailing edges 48′ will draw blood 17 out of the aneurysm20 and back into the blood flow 17 in the lumen 16, thereby collapsingthe bubble 20, or at least decreasing it.

In the second embodiment, as depicted in FIGS. 7A and 7B, each coilportion 62 of a flexible wire coil intra-vascular stent 60 includes anupstream leading edge 64, an outer surface 66, a downstream trailingedge 68, and an inner surface 70. In the second embodiment of FIGS. 7Aand 7B, the outer surface 66 defines a convex surface between theleading edge 64 and the trailing edge 68, whereas the inner surface 70defines a concave surface between the leading edge 64 and the trailingedge 68. Moreover, whereas several of the outer surfaces 66 face theinner wall 12 of the blood vessel 10, and the inner surfaces 70 all facethe lumen 16 of the blood vessel 10, selected coil portions 62′ haveouter surfaces 66′ facing the neck 18 into the aneurysm 20.

In operation, blood flow 17 in the lumen 16 will flow into and out ofthe concave inner surfaces 70, with some blood flow 17 being diverted bythe leading edges 64′ of the selected coil portions 62′ proximate theneck 18, across the convex outer surfaces 66′, past the trailing edges68′ and back towards the lumen 16. As discussed above with respect tothe embodiment of FIG. 6A, some of the blood 17 in the aneurysm 20 willbecome entrained in the blood flow 17 passing across the outer surfaces66′ and will flow back into the lumen 16. More significantly, theconverging blood flow paths 17 at the selected trailing edges 68′ createeddies 72 proximate the trailing edges 68′ of the selected coil portions62′, each eddy 72 resulting in a pressure drop dP between pressure atthe respective convex outer surface 66′ and the respective trailing edge68′. In the location of the selected coil portions 62′, the dP generatedat the respective trailing edges 68′ will draw blood 17 out of theaneurysm 20 and back into the blood flow 17 in the lumen 16, therebycollapsing the bubble 20, or at least decreasing it.

What is claimed is:
 1. An intra-vascular aneurysm-treatment stentcomprising: a flexible member, insertable into a blood vessel, withselected portions of the flexible member positioned proximate an openingin a wall of the blood vessel, and opening into an aneurysm bubble, theflexible member having an upstream proximal end, an opposite downstreamdistal end, a length between the proximal end and the distal end, and alongitudinal axis extending along the length, the selected portions ofthe flexible member each having a leading edge directed toward theproximal end, a trailing edge directed toward the distal end, and anouter surface and an inner substantially planar surface extending fromproximate the leading edges to proximate the trailing edges, at leastone of the selected portions having a first cross-section in a firstplane parallel to the longitudinal axis, the inner substantially planarsurface being located at or above a second plane perpendicular to thefirst plane and parallel to the longitudinal axis, a third planeperpendicular to the first plane and the second plane, the third planeintersecting the first cross-section between the leading edge and thetrailing edge in the first cross-section, and the third planeintersecting the second plane, a fourth plane perpendicular to the firstplane and the second plane, the fourth plane intersecting the firstcross-section between the leading end and the intersection of the thirdplane with the first cross-section, a fifth plane perpendicular to thefirst plane the second plane, the fifth plane intersecting the firstcross-section between the trailing end and the intersection of the thirdplane with the first cross-section, a distance between the outer surfaceand the inner surface in the first cross-section at the intersection ofthe third plane being greater than a distance between the outer surfaceand the inner surface in the first cross-section at each of theintersections of the fourth and fifth planes, the flexible member havinga maximum distance between the outer surface and the second plane in thethird plane; wherein the selected portions of the flexible member areconfigured to receive blood flow at respective upstream leading edges,direct first portions of the blood flow over the outer surfaces andsecond portions of the blood flow across the inner surfaces, the firstblood flow portions converging with the second blood flow portions atrespective trailing edges, the converging first and second blood flowportions at least temporarily directing blood away from the aneurysmbubble and back into the blood vessel.
 2. The intra-vascularaneurysm-treatment stent of claim 1, wherein a sixth plane isperpendicular to the first plane and the second plane intersects thefirst cross- section between the intersections of the third plane andthe fourth plane with the first cross-section, a distance between theouter surface and the inner surface in the first cross-section at theintersection of the sixth plane being less than the distance between theouter surface and the inner surface in the first cross-section at theintersection of the third plane, and the distance between the outersurface and the inner surface in the first cross-section at theintersection of the sixth plane being greater than the distance betweenthe outer surface and the inner surface in the first cross-section atthe intersection of the fourth plane.
 3. The intra-vascularaneurysm-treatment stent of claim 2, wherein a seventh plane isperpendicular to the first plane and the second plane intersecting thefirst cross-section between the intersections of the third plane and thefifth plane with the first cross-section, a distance between the outersurface and the inner surface in the first cross-section at theintersection of the seventh plane being less than the distance betweenthe outer surface and the inner surface in the first cross-section atthe intersection of the third plane, and the distance between the outersurface and the inner surface in the first cross-section at theintersection of the seventh plane being greater than the distancebetween the outer surface and the inner surface in the firstcross-section at the intersection of the fifth plane.
 4. Theintra-vascular aneurysm-treatment stent of claim 3, wherein an eighthplane is perpendicular to the first plane and the second planeintersects the first cross-section between the leading end and theintersection of the fourth plane with the first cross-section, and adistance between the outer surface and the inner surface in the firstcross-section at the intersection of the eighth plane being less thanthe distance between the outer surface and the inner surface in thefirst cross-section at the intersection of the fourth plane.
 5. Theintra-vascular aneurysm-treatment stent of claim 4, wherein a ninthplane is perpendicular to the first plane and the second planeintersects the first cross-section between the trailing end and theintersection of the fifth plane with the first cross-section, and adistance between the outer surface and the inner surface in the firstcross-section at the intersection of the ninth plane being less than thedistance between the outer surface and the inner surface in the firstcross-section at the intersection of the fifth plane.
 6. Theintra-vascular aneurysm-treatment stent of claim 1, wherein the flexiblemember is configured as a coil.
 7. The intra-vascular aneurysm-treatmentstent of claim 1, wherein the flexible member is configured as anexpanding generally tubular stent.
 8. The intra-vascularaneurysm-treatment stent of claim 1, wherein the outer surfaces aresubstantially convex.
 9. The intra-vascular aneurysm-treatment stent ofclaim 1, wherein the inner substantially planar surfaces aresubstantially flat.
 10. The intra-vascular aneurysm-treatment stent ofclaim 1, wherein the selected flexible member portions are configured todefine eddies in the blood flow path proximate each of the trailingedges.
 11. The intra-vascular aneurysm-treatment stent of claim 1,wherein the flexible member is configured to be inserted into the bloodvessel proximate a saccular aneurysm.
 12. The intra-vascularaneurysm-treatment stent of claim 1, wherein the flexible member isconfigured to be inserted into the blood vessel proximate a fusiformaneurysm.
 13. The intra-vascular aneurysm-treatment stent of claim 1,wherein the selected portions of the flexible member each have a lengthbetween the leading edges and the trailing edges, the selected portionsof the flexible member each having a maximum height between the outersurfaces and the inner surfaces, the lengths of the selected portions ofthe flexible member being greater than the maximum heights of theselected portions of the flexible member.
 14. An intra-vascularaneurysm-treatment stent comprising: a flexible coil, insertable into ablood vessel, with selected portions of the coil positioned proximate anopening in a wall of the blood vessel, and opening into an aneurysmbubble, the coil having an upstream proximal end, an opposite downstreamdistal end, a length between the proximal end and the distal end, and alongitudinal axis extending along the length, the selected portions ofthe coil each having a leading edge directed toward the proximal end, atrailing edge directed toward the distal end, and an outer surface andan inner surface extending from proximate the leading edges to proximatethe trailing edges, at least one of the selected portions having a firstcross-section in a first plane parallel to the longitudinal axis, theouter surface in the first cross-section having a first end and anopposite second end, and the inner surface in the first cross-sectionhaving a third end and an opposite fourth end, the first, second, third,and fourth ends terminating at a second plane perpendicular to the firstplane and parallel to the longitudinal axis, the inner surface beinglocated at or above the second plane, a third plane perpendicular to thefirst plane and the second plane, the third plane intersecting the firstcross-section between the leading edge and the trailing edge in thefirst cross-section, and the third plane intersecting the second plane,a fourth plane perpendicular to the first plane and the second plane,the fourth plane intersecting the first cross-section between theleading end and the intersection of the third plane with the firstcross-section, a fifth plane perpendicular to the first plane and thesecond plane, the fifth plane intersecting the first cross-sectionbetween the trailing end and the intersection of the third plane withthe first cross-section, a distance between the outer surface and thesecond plane in the first cross-section at the intersection of the thirdplane being greater than a distance between the outer surface and thesecond plane in the first cross-section at each of the intersections ofthe fourth and fifth planes, a distance between the inner surface andthe second plane in the first cross-section at the intersection of thethird plane being greater than a distance between the inner surface andthe second plane in the first cross-section at each of the intersectionsof the fourth and fifth planes, the flexible member having a maximumdistance between the outer surface and the second plane in the thirdplane; wherein the selected portions of the coil are configured toreceive blood flow at respective upstream leading edges, direct firstportions of the blood flow over the outer surfaces and second portionsof the blood flow across the inner surfaces, the first blood flowportions converging with the second blood flow portions at respectivetrailing edges, the converging first and second blood flow portions atleast temporarily directing blood away from the aneurysm bubble and backinto the blood vessel.
 15. The intra-vascular aneurysm-treatment stentof claim 14, wherein a sixth plane is perpendicular to the first planeand the second plane, and the sixth plane intersects the firstcross-section between the intersections of the third plane and thefourth plane with the first cross-section, a distance between the outersurface and the second plane in the first cross-section at theintersection of the sixth plane being less than the distance between theouter surface and the second plane in the first cross-section at theintersection of the third plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the sixth plane being less than the distance between theinner surface and the second plane in the first cross-section at theintersection of the third plane.
 16. The intra-vascularaneurysm-treatment stent of claim 15, wherein a seventh plane isperpendicular to the first plane and the second plane, and the seventhplane intersects the first cross-section between the leading end and thefourth plane with the first cross-section, a distance between the outersurface and the second plane in the first cross-section at theintersection of the seventh plane being less than the distance betweenthe outer surface and the second plane in the first cross-section at theintersection of the fourth plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the seventh plane being less than the distance betweenthe inner surface and the second plane in the first cross-section at theintersection of the fourth plane.
 17. The intra-vascularaneurysm-treatment stent of claim 16, wherein an eighth plane isperpendicular to the first plane and the second plane, and the eighthplane intersects the first cross-section between the intersections ofthe third plane and the fifth plane with the first cross-section, adistance between the outer surface and the second plane in the firstcross-section at the intersection of the eighth plane being less thanthe distance between the outer surface and the second plane in the firstcross-section at the intersection of the third plane, and a distancebetween the inner surface and the second plane in the firstcross-section at the intersection of the eighth plane being less thanthe distance between the inner surface and the second plane in the firstcross-section at the intersection of the third plane.
 18. Theintra-vascular aneurysm-treatment stent of claim 17, wherein a ninthplane is perpendicular to the first plane and the second plane, and theninth plane intersects the first cross-section between the trailing endand the fifth plane with the first cross-section, a distance between theouter surface and the second plane in the first cross-section at theintersection of the ninth plane being less than the distance between theouter surface and the second plane in the first cross-section at theintersection of the fifth plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the ninth plane being less than the distance between theinner surface and the second plane in the first cross-section at theintersection of the fifth plane.
 19. The intra-vascularaneurysm-treatment stent of claim 14, wherein the flexible member isconfigured as a coil.
 20. The intra-vascular aneurysm-treatment stent ofclaim 14, wherein the flexible member is configured as an expandinggenerally tubular stent.
 21. The intra-vascular aneurysm-treatment stentof claim 14, wherein the outer surfaces are substantially convex. 22.The intra-vascular aneurysm-treatment stent of claim 14, wherein theinner substantially planar surfaces are substantially flat.
 23. Theintra-vascular aneurysm-treatment stent of claim 14, wherein theselected flexible member portions are configured to define eddies in theblood flow path proximate each of the trailing edges.
 24. Theintra-vascular aneurysm-treatment stent of claim 14, wherein theflexible member is configured to be inserted into the blood vesselproximate a saccular aneurysm.
 25. The intra-vascular aneurysm-treatmentstent of claim 14, wherein the flexible member is configured to beinserted into the blood vessel proximate a fusiform aneurysm.
 26. Theintra-vascular aneurysm-treatment stent of claim 14, wherein theselected portions of the flexible member each have a length between theleading edges and the trailing edges, the selected portions of theflexible member each having a maximum height between the outer surfacesand the inner surfaces, the lengths of the selected portions of theflexible member being greater than the maximum heights of the selectedportions of the flexible member.
 27. An intra-vascularaneurysm-treatment stent comprising: a flexible coil, insertable into ablood vessel, with selected portions of the coil positioned proximate anopening in a wall of the blood vessel, and opening into an aneurysmbubble, the coil having an upstream proximal end, an opposite downstreamdistal end, a length between the proximal end and the distal end, and alongitudinal axis extending along the length, the selected portions ofthe coil each having a leading edge directed toward the proximal end, atrailing edge directed toward the distal end, and an outer surface andan inner surface extending from proximate the leading edges to proximatethe trailing edges, at least one of the selected portions having a firstcross-section in a first plane parallel to the longitudinal axis, theouter surface in the first cross-section having a first end and anopposite second end, the first and second ends terminating at a secondplane perpendicular to the first plane and parallel to the longitudinalaxis, the inner surface being located at or above the second plane, athird plane perpendicular to the first plane and the second plane, thethird plane intersecting the first cross-section between the first endand the second end in the first cross-section, and the third planeintersecting the second plane, a fourth plane perpendicular to the firstplane and the second plane, the fourth plane intersecting the firstcross-section between the first end and the intersection of the thirdplane with the first cross-section, a fifth plane perpendicular to thefirst plane and the second plane, the fifth plane intersecting the firstcross-section between the second end and the intersection of the thirdplane with the first cross-section, a distance between the outer surfaceand the second plane in the first cross-section at the intersection ofthe third plane being greater than a distance between the outer surfaceand the second plane in the first cross-section at each of theintersections of the fourth and fifth planes, the flexible member havinga maximum distance between the outer surface and the second plane in thethird plane; wherein the selected portions of the coil are configured toreceive blood flow at respective upstream leading edges, direct firstportions of the blood flow over the outer surfaces and second portionsof the blood flow across the inner surfaces, the first blood flowportions converging with the second blood flow portions at respectivetrailing edges, the converging first and second blood flow portions atleast temporarily directing blood away from the aneurysm bubble and backinto the blood vessel.
 28. The intra-vascular aneurysm-treatment stentof claim 27, wherein a sixth plane is perpendicular to the first planeand the second plane, and the sixth plane intersects the firstcross-section between the intersections of the third plane and thefourth plane with the first cross-section, a distance between the outersurface and the second plane in the first cross-section at theintersection of the sixth plane being less than the distance between theouter surface and the second plane in the first cross-section at theintersection of the third plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the sixth plane being less than the distance between theinner surface and the second plane in the first cross-section at theintersection of the third plane.
 29. The intra-vascularaneurysm-treatment stent of claim 28, wherein a seventh is planeperpendicular to the first plane and the second plane, and the seventhplane intersects the first cross-section between the leading end and thefourth plane with the first cross-section, a distance between the outersurface and the second plane in the first cross-section at theintersection of the seventh plane being less than the distance betweenthe outer surface and the second plane in the first cross-section at theintersection of the fourth plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the seventh plane being less than the distance betweenthe inner surface and the second plane in the first cross-section at theintersection of the fourth plane.
 30. The intra-vascularaneurysm-treatment stent of claim 29, wherein an eighth plane isperpendicular to the first plane and the second plane, and the eighthplane intersects the first cross-section between the intersections ofthe third plane and the fifth plane with the first cross-section, adistance between the outer surface and the second plane in the firstcross-section at the intersection of the eighth plane being less thanthe distance between the outer surface and the second plane in the firstcross-section at the intersection of the third plane, and a distancebetween the inner surface and the second plane in the firstcross-section at the intersection of the eighth plane being less thanthe distance between the inner surface and the second plane in the firstcross-section at the intersection of the third plane.
 31. Theintra-vascular aneurysm-treatment stent of claim 30, wherein a ninthplane is perpendicular to the first plane and the second plane, and theninth plane intersects the first cross-section between the trailing endand the fifth plane with the first cross-section, a distance between theouter surface and the second plane in the first cross-section at theintersection of the ninth plane being less than the distance between theouter surface and the second plane in the first cross-section at theintersection of the fifth plane, and a distance between the innersurface and the second plane in the first cross-section at theintersection of the ninth plane being less than the distance between theinner surface and the second plane in the first cross-section at theintersection of the fifth plane.
 32. The intra-vascularaneurysm-treatment stent of claim 27, wherein the flexible member isconfigured as a coil.
 33. The intra-vascular aneurysm-treatment stent ofclaim 27, wherein the flexible member is configured as an expandinggenerally tubular stent.
 34. The intra-vascular aneurysm-treatment stentof claim 27, wherein the outer surfaces are substantially convex. 35.The intra-vascular aneurysm-treatment stent of claim 27, wherein theinner substantially planar surfaces are substantially flat.
 36. Theintra-vascular aneurysm-treatment stent of claim 27, wherein theselected flexible member portions are configured to define eddies in theblood flow path proximate each of the trailing edges.
 37. Theintra-vascular aneurysm-treatment stent of claim 27, wherein theflexible member is configured to be inserted into the blood vesselproximate a saccular aneurysm.
 38. The intra-vascular aneurysm-treatmentstent of claim 27, wherein the flexible member is configured to beinserted into the blood vessel proximate a fusiform aneurysm.
 39. Theintra-vascular aneurysm-treatment stent of claim 27, wherein theselected portions of the flexible member each have a length between theleading edges and the trailing edges, the selected portions of theflexible member each having a maximum height between the outer surfacesand the inner surfaces, the lengths of the selected portions of theflexible member being greater than the maximum heights of the selectedportions of the flexible member.